This invention relates to a tone signal generation device used for an electronic musical instrument and other tone generation devices and, more particularly, to a tone signal generation device capable of changing tone elements such as tone color sequentially at each timing of generation of a tone.
This invention further relates to a tone signal generation device capable of generating a tone signal in channels in which tone elements such as tone color are different from one another.
U.S. Pat. No. 4,214,500 discloses a tone signal generation device in which tone elements such as pitch, tone color and tone envelope of a tone to be generated are changed randomly at each timing of generating the tone. In this prior art device, tone elements such as pitch, tone color and tone volume envelope of a tone to be generated are independently controlled in plural tone forming channels and sounding of tones of depressed keys is assigned in accordance with a normal tone generation assignment principle (i.e., tone generation is assigned to an empty channel if there is one whereas, if there is no such empty channel, it is assigned in accordance with truncating processing to a channel in which the oldest released key exists or in which attenuation of the tone has progressed to the furthest degree). Accordingly, relationship between the order of depression of keys (i.e., order of sounding of tones) and a channel to which tone generation is assigned is entirely random and, as a result, tone elements such as pitch, tone color and tone volume envelope of a tone to be generated change randomly at each timing of generation of a tone.
In the above described prior art device, pitch, tone color and tone volume envelope of a tone to be generated can be changed only randomly so that only a random performance effect can be obtained.
U.S. Pat. No. 4,387,617 discloses a device in which generation of a tone corresponding to one depressed key is assigned to channels which are different depending upon tone colors and plural tone signals corresponding to the same depressed key are thereby generated with different tone colors in different channels. If, for example, tone colors 1 and 2 have been selected and keys C4 and D4 have been depressed, the key C4 and the tone color 1 are assigned to channel 1, the key C4 and the tone color 2 are assigned to channel 2, the key D4 and the tone color 1 are assigned to channel 3 and the key D4 and the tone color 2 are assigned to channel 4. In this manner, tone generation is assigned to plural channels in correspondence to all combinations of selected number of tone colors and selected number of depressed keys.
When plural tone colors have been selected in the above described prior art device, tones of plural channels of the same number as the number of the tone colors are automatically generated and all tones of the depressed keys become automatically tones of plural channels. It was not possible in the prior art device to easily perform a complicated multi-channel control such as sounding tones of a part of depressed keys as multi-channel tones while sounding the rest of tones as a single channel tone and differing the number of channels between tones of a part of the depressed keys and the rest of tones.